Process for the manufacture of yarns from hydroxylated polyvinyl compounds



April 1, 1952 N. DRISCH ETAL 2,591,242

PROCESS FOR THE MANUFACTURE OF YARNS FROM HYDROXYLATED POLYVINYL COMPOUNDS Filed Jan. 19, 1950 Patented Apr. 1, 195.2

UNITED STATES PATENT OFFICE rnoonss FOR THE MANUFACTURE OF YARNS FROM HYDROXYLATED POLY- VINYL COMPOUNDS Nicolas Drisch and Paul Herrbach, Paris, France, assigncrs, by mesne assignments, to Textile and Chemical Research Company Limited, St. Peter Port, Guernsey, Channel Islands, a corporation of Great Britain Application January 19, 1950, Serial No. 139,458 In France February 1, 1949 Claims.

1 This invention relates to the manufacture of spun yarn from hydroxylated polyvinyl compounds in an ammonium sulphate spinning bath The spinning of soluble rayon may be accom--,

plished with the aid of various hydrophilic substances such as sodium alginate, carboxymethyl cellulose, etc.

Filaments obtained from sodium alginate solutions are lacking in elongation. They will not dissolve in aqueous medium, but only in slightly alkaline medium. Alginate threads are generally based on the calcium salt of alginic acid.

Filamentsof the aluminum salt of celluloseglycolic acid are not readily soluble in weak alkaline medium, but require more strongly a1kaline media which may be harmful to the wool with which such products are often mixed.

The spinning of solutions of hydroxylated polyvinyl compounds is described in general in United States Patent No. 2,388,325. For example, aqueous solutions of polyvinyl alcohol are spun in a hot aqueous bath containing 35 per cent of ammonium sulphate. The filaments so obtained are stretched and collected in a spinning pot. The spinning is done with the usual equipment used for artificial textiles. The filaments obtained, impregnated with ammonium sulphate, are subjected to washing by a solution of 50 per cent acetone in water. This washing is tedious and difiioult because of the low solubility of ammonium sulphate in the solvent mixture. Before drying, the cakes are re-treated with pure acetone.

Among the disadvantages of this process are the need for an organicsolvent which must be recovered, the danger of explosion of the solvent air mixture, and the solvent lossep.

The present invention provides a simpler and more economical method of manufacturing yarn from hydroxylated poiyvinyl compounds, such as polyvinyl alcohol.

According to the invention, the cakes of yarn are dried in a ventilated hot air drier, producing a package of yarn carrying ammonium sulphate in the form of an impalpably line powder not affecting the strength of the individual filaments. The cake is re-wound by passing the yarn through a tensioning device set to introduce friction adapted to remove most of the ammonium sulphate powder coating the yarn. The yarn obtained is characterized by a very soft feel, complete independence of all filaments, and very satisfactory mechanical properties. The following example will afford a clearer understanding of the invention, but is of course in no way restrictive.

Eazample A solution of 15 per cent polyvinyl alcohol of low viscosity is prepared by heating with water. This solution is readily filterable, even after cooling and has a viscosity of about 115 poises at 20 C. It is desirable to add 1 per cent of lauryl pyridinium chloride calculated on the polyvinyl alcohol. The resulting solution is filtered and deaerated.

The spinning is effected in a known way. The solution is spun in an aqueous bath containing 35 per cent ammonium sulphate at C. from a spinneret having 30 holes of /100 mm. The thread is stretched 410 per cent between two rollers, the final speed being 40 to min. The feed of the solution is controlled so as to yield 5 d. filaments. The resulting yarn is collected in cakes in a spinning pot with a speed of 6000 R. P. M. The resulting cakes are dried at C. in a ventilated drier. They are unwound on ordinary spoolers, with the filament passing through a tensioning device set to produce tensions of the order of 1 gram per denier, e. g. in a grid tensioning device, to scrape ad the adhering saline powder.

In the drawing the figure is a diagrammatic representation of one type of apparatus in which this process can be carried out.

Referring to the drawing the cake it of yarn II is unwound through guides 12 and I3 onto a spool 14 which is driven by a drive roller 15. Interposed between the guides I2 and I3 is a grid tensioning and scraping device comprising sets of bars i6 and H which are interleaved and around which the yarn passes. The friction produced by the bars is controlled by varying the overlap of the two sets of bars. In operation the bars introduce sufiicient friction to scrape the ammonium sulphate powder from the yarn as above described.

The resulting yarn has a dry strength of 1.90 grams per denier with an elongation at break of 40 per cent, and contains only a few per cent of salts, not enough to interfere with its use. It is very bright, flexible and soluble in water. It is suitable for all applications of soluble threads such as the manufacture of artificial embroidery or the like. i

What is claimed is:

1. The method of producing spun yarns from aqueous solutions of polyvinyl alcohol which comprises spinning said solution into a concentrated aqueous saline solution, stretching the spun filaments during the spinning operation, winding the yarn thus produced onto a package, drying the package to produce a yarn having adherent powder thereon, and rewinding the yarn from said package while passing the yarn with the adherent powder thereon over stationary friction members to scrape the adherent powder from the surface thereof.

2. The method of producing spun yarns from aqueous solutions of polyvinyl alcohol which comprises spinning said solution into a concentrated aqueous saline solution, stretching the spun filaments during the spinning operation, winding the yarn thus produced onto a package, drying the package to produce a yarn havin adherent powder thereon, and rewinding the yarn from said package while passing the yarn with the adherent powder thereon over interleaved bars to apply friction to scrape the adherent'powder from the surface thereof. a

3.- The method of producing spun yarns from aqueous solutions of polyvinyl alcohol which comprises spinning said solution into a concentrated aqueous saline solution, stretching the spun filaments during the spinning operation, winding the yarn thus produced onto a package, drying the package at a slightly elevated temperature with circulation of air thereover to produce a yarn having adherent powder thereon, and rewinding the yarn from said package while passing the yarn with the adherent powder thereon over stationary friction members to scrape the adherent powder from the surface thereof.

4. The method of producingspun yarns from aqueous solutions of polyvinyl alcohol which comprises spinning said solution into a concentrated aqueous solution of ammonium sulphate, stretching the spun filaments during the spinning operation, winding the yarn thus produced onto a package, drying the package to provide a yarn having ammonium sulphate powdernadhering thereto, and rewinding the'yarn from said package while passing the yarn with the adherent powder thereon over stationary friction members to scrape the adherent powder from the surface thereof.

5. 'The method of producing spun yarns from aqueous solutions of polyvinyl alcohol which comprises spinning said solution into a concentrated aqueous saline solution, stretching the spun filaments during the spinning operation, winding the yarn thus produced onto a package, drying the package to produce a yarn havin adherent powder thereon, and rewinding the yarn from said package while" applying a stretching tension of approximately lgram per denier and scraping adherent powder from the surface thereof.

NICOLAS DRISCH. PAUL HERRBACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Houtz Nov. 6, 1945 

1. THE METHOD OF PRODUCING SPUN YARNS FROM AQUEOUS SOLUTIONS OF POLYVINYL ALCOHOL WHICH COMPRISES SPINNING SAID SOLUTION INTO A CONCENTRATED AQUEOUS SALINE SOLUTION, STRETCHING THE SPUN FILAMENTS DURING THE SPINNING OPERATION, WINDING THE YARN THUS PRODUCED ONTO A PACKAGE, DRYING THE PACKAGE TO PRODUCE A YARN HAVING ADHERENT POWDER THEREON, AND REWINDING THE YARN FROM SAID PACKAGE WHILE PASSING THE YARN WITH THE ADHERENT POWDER THEREON OVER STATIONARY FRICTION MEMBERS TO SCRAPE THE ADHERENT POWDER FROM THE SURFACE THEREOF. 